Research shows that violent video games increase aggressive behavior and decrease prosocial behavior, but could relaxing video games have the opposite effects? In two experiments, participants were randomly assigned to play a relaxing, neutral, or prosocial video game for 20 min. In Experiment 1, participants competed with an ostensible partner on a competitive reaction time task in which they could behave in an aggressive manner (by blasting their partner with loud noise), or in a prosocial manner (by giving their partner money). In Experiment 2, participants reported their mood after playing the video game. After the study was over, they could help the experimenter by sharpening pencils. Compared to those who played violent or neutral video games, those who played relaxing video games were less aggressive and more helpful. Playing a relaxing video game put people in a good mood, and those in a good mood were more helpful. © The Author(s) 2012.